1. Field of the Invention
The present invention relates to a zoom lens barrel.
2. Description of the Related Art
In a known zoom lens barrel of a zoom compact camera, etc., a cylindrical member which constitutes a lens barrel is provided on its inner peripheral surface with a plurality of guide grooves extending in different directions, to guide internal moving members or lens groups, etc. In order to achieve further miniaturization of the zoom lens barrel, a construction wherein the guide grooves intersect has been proposed. However, in such a construction, it is necessary to prevent radial guide projections which are guided in corresponding guide grooves from being disengaged therefrom or from entering other guide grooves at the intersections of the guide grooves. For instance, the lens barrel is provided on its inner peripheral surface with an axial groove extending in parallel with the optical axis and a circumferential groove intersecting the axial groove, so that when the lens barrel member having the axial groove is rotated to apply a force to a radial projection which is fitted in the axial groove, the inner moving member having the radial projection is moved in the optical axis direction. In this arrangement, the radial projection is moved in the axial directions while being subject to a rotational force in the circumferential direction. Therefore, there is a possibility that the radial projection is disengaged from the axial groove and enters the circumferential groove at the intersection of the axial groove and the circumferential groove, due to the circumferential force. Also, there is a possibility that the radial projection fitted in the circumferential groove is disengaged therefrom at the intersection with the axial groove.
It is an object of the present invention to provide a zoom lens barrel in which it is possible to prevent a radial projection, which is guided in a plurality of guide grooves which intersect each other, from being disengaged from the associated guide grooves at the intersection thereof.
To achieve the object mentioned above, according to an aspect of the present invention, a zoom lens barrel is provided, including a first cylindrical member having first and second bottomed grooves on an inner peripheral surface thereof, the first and second grooves having different profiles, wherein the first and second bottomed grooves intersect each other; a first moving member which is provided with a first radial projection which is fitted in the first bottomed groove, the first moving member being movable relative to the first cylindrical member in accordance with the profile of the first bottomed groove; and a second moving member which is provided with a second radial projection which is fitted in the second bottomed groove, the second moving member being movable relative to the first cylindrical member in accordance the profile of the second bottomed groove. The shapes of the first bottomed groove and the first radial projection and the shapes of the second bottomed groove and the second radial projection are such that the second radial projection cannot be fitted in the first bottomed groove and that the first radial projection cannot be fitted in the second bottomed groove.
Preferably, the first cylindrical member having the first and second bottomed grooves is driven and rotated by a rotational drive device, the first moving member defines a second cylindrical member which is guided to move in an optical axis direction within the first cylindrical member, and the second moving member defines a third cylindrical member which is guided to rotate and move in the optical axis direction within the second cylindrical member.
The first bottomed groove is a circumferential groove about an optical axis; and the second bottomed groove is an axial groove extending in parallel with the optical axis.
In an embodiment, a length of the first radial projection along the first groove is greater than a width of the second groove, and a length of the second radial projection along the second groove is greater than a width of the first groove.
In another embodiment, the first and second grooves are bottomed grooves; one of the first and second radial projections is longer, in a radial direction thereof, than a depth of the groove in which the other of the first and second radial projections is fitted; and a length of the one of the first and second radial projections, along the groove in which the one of the first and second radial projection is fitted, is greater than a width of the groove in which the other of the first and second radial projection is fitted.
According to another aspect of the present invention a zoom lens barrel is provided, including a first cylindrical member having, on an inner peripheral surface thereof, an axial groove extending in parallel with an optical axis and a circumferential groove extending in the circumferential direction about the optical axis, the circumferential groove intersecting the axial groove; a first moving member which is provided with a circumferential guide projection which is fitted in the circumferential groove, the first moving member being movable relative to the first cylindrical member in accordance with the profile of the circumferential groove; and a second moving member which is provided with an axial guide projection which is fitted in the axial groove, the second moving member being movable relative to the first cylindrical member in accordance with the profile of the axial groove. The engagement length of the circumferential guide projection and the circumferential groove, in at least one of the circumferential direction and the radial direction perpendicular to the optical axis, is greater than the circumferential width or radial depth of the axial groove. The engagement length of the axial guide projection and the axial groove, in at least one of the axial direction and the radial direction perpendicular to the optical axis, is greater than the axial width or radial depth of the circumferential groove.
According to another aspect of the present invention a barrel assembly used in a zoom lens barrel is provided, including a first cylindrical member having, on an inner peripheral surface thereof, an axial groove extending in parallel with an optical axis and a circumferential groove extending in the circumferential direction about the optical axis, the circumferential groove intersecting the axial groove; a first moving barrel which is provided with a circumferential guide projection which is fitted in the circumferential groove, the first moving barrel being movable relative to the first cylindrical member in accordance with the profile of the circumferential groove; and a second moving barrel which is provided with an axial guide projection which is fitted in the axial groove, the second moving barrel being movable relative to the first cylindrical member in accordance with the profile of the axial groove. The engagement length of the circumferential guide projection and the circumferential groove, in at least one of the circumferential direction and the radial direction perpendicular to the optical axis, is greater than the circumferential width or radial depth of the axial groove. The engagement length of the axial guide projection and the axial groove, in at least one of the axial direction and the radial direction perpendicular to the optical axis, is greater than the axial width or radial depth of the circumferential groove.
With the two above-described arrangements, since the circumferential guide projection and the axial guide projection are engaged in the corresponding circumferential groove and the axial groove in at least one of the slide movement direction and the radial direction, no disengagement of the guide projections from the associated grooves takes place even at the intersections of the grooves.
The structure to prevent the circumferential and radial guide projections from being disengaged from the associated grooves can be embodied as follows. Namely, the axial guide projection can be provided with a pair of parallel planar surfaces which are brought into sliding contact with a pair of opposed wall surfaces of the axial groove which extend in the optical axis direction, the planar surfaces having axial lengths greater than the axial width of the circumferential groove; wherein the circumferential length of the circumferential guide projection is greater than the circumferential width of the axial groove.
Consequently, in this arrangement in which the radial and circumferential projections are elongated in the direction of the slide movement thereof, since the amount of engagement thereof with the corresponding grooves in the radial direction can be reduced, the lens barrel can be made small. From the viewpoint of the miniaturization of the lens barrel, it is preferable that the radial depth of the axial groove be substantially identical to the radial depth of the circumferential groove.
Likewise, in an embodiment, the axial guide projection is provided with a pair of parallel planar surfaces which are brought into sliding contact with a pair of opposed wall surfaces of the axial groove which extend in the optical axis direction, the planar surfaces having axial lengths greater than the axial width of the circumferential groove; wherein the radial depth of the circumferential groove is greater than the radial depth of the axial groove, the circumferential guide projection being fitted in the circumferential groove so that the length of projection of the circumferential guide projection in the radial direction is greater than the depth of the axial groove.
In this arrangement, the radial depth of the circumferential groove is greater than the radial depth of the axial groove, and the circumferential guide projection is fitted in the circumferential groove, so that the length of projection of the circumferential guide projection in the radial direction is greater than the depth of the axial groove. Consequently, the circumferential length of the circumferential guide projection is smaller than the circumferential width of the axial groove.
In an embodiment, the radial depth of the axial groove is greater than the radial depth of the circumferential groove, the axial guide projection being fitted in the axial groove so that the length of projection thereof in the radial direction is greater than the depth of the circumferential groove; wherein the circumferential length of the circumferential guide projection is greater than the circumferential width of the axial groove.
In this structure, the axial guide projection is in the form of a cylinder which is brought into contact at opposite longitudinal sides of the cylinder with a pair of opposed wall surfaces, which extend in the optical axis direction, of the axial groove.
In an embodiment, the first cylindrical member is driven and rotated by a rotational drive device; wherein the first moving member defines a second cylindrical member which is guided to move in an optical axis direction within the first cylindrical member; the second moving member defines a third cylindrical member which is guided to move in the optical axis direction within the second cylindrical member, while being rotated relative to the second cylindrical member in accordance with the rotation of the first cylindrical member in accordance with the profile of the axial groove; and the second cylindrical member is provided with a through groove through which the axial guide projection of the third cylindrical member extends.
In this structure, the axial guide projection can be made of a cylinder which is brought into contact with a pair of opposed wall surfaces of the axial groove in the optical axis direction at radial lines.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-305224 (filed on Oct. 27, 1999) which is expressly incorporated herein by reference in its entirety.